120 
of the disease in the Seychelles islands is of recent date suggests the 
idea that impaired vitality of the vanilla plants may favour the spread 
of the disease. - is not known whether vigorous growing vanilla plants 
ean be i almost certain that "weakly specimens would be 
the statement accompanying the material that the disease 
on the dead leaves ci entirely on moisture; if the leaves remain 
ui 
a considerable length of time, and on being moistened resume their 
activity. In like manner it is probable that the mycelium of the Hainsea 
stage in the living tissues may under certain conditions remain for 
a considerable time in the leaves and stem without showing itself 
externally ; hence it would be highly imprudent to use even apparently 
healthy plants obtained from infected areas for stocking new estates. 
I : : 
disease have been followed on cultivated orchids at Kew, belonging to 
the genera Oncidium and Dendrobium. 
GEORGE MASSEE. 

Exeraxaniox OF THE PLATE. 
Fig. L Portions of stem, leaf, and aerial root of Vanilla planifolia, 
— the Cytispora and Calospora stages of disease; nat. 
Fig. en "Section M a pustule of the Hainsea stage of the 
disease 800 
Fig. III, Bosw ae germinating; x 400. 
Fig. IV. iors: gonidia of Hainsea reproducing themselves by 
budding; x 400. 
Fig. 'V. ‘Section through m and portion of stroma of the 
C, ra form; a, a’, stroma; b, 6’, b”, pycnidia in various 
stages of devélopineht x "960. 
Fig. VI. Section through perithecia and portion of stroma of 
Calospora vanille; a, a’, stroma; b, b', b", perithecia in 
various stages of development ; Lx 250. 
Fig. VII. Ascus containing spores and paraphyses of the same; 
x 400. 

